MoDisco/CodingConventions

Eclipse JDT Warnings Level

For code style verification, it is recommended to configure Eclipse JDT settings for errors/warning levels : all rules levels set as "ignored" should be set as "warning".

Some rules might create too many constraints on Java code in some circumstances. The developer is allowed to deactivate the rules in specific areas :

- with projects specific errors/warning levels.

- with @SuppressWarnings, adding some explanation to justify the deviation.

Eclipse JDT Levels for EMF generated classes

For instance, here are the typical project settings to "ignore" level for a Java EMF generated project : - Unqualified Access to instance field - Undocumented empty block - Parameter assignment - Boxing and unboxing conversions - Field declaration hides another field - Parameter is never read - Unused import - Unnecessary 'else' - Unnecessary cast or 'instanceof' operation

Checkstyle Usage

For MoDisco internal developments, the org.eclipse.gmt.modisco.dev.core project defines a MoDisco.checkstyle file. This file defines coding rules. It was initiated from the "Sun Checks (Eclipse)" default configuration. Some rules which were deemed too restrictive have been disabled.

This project is available in SVN: https://dev.eclipse.org/svnroot/modeling/org.eclipse.gmt.modisco/plugins/trunk/org.eclipse.gmt.modisco.dev.core/checkstyle/MoDisco.checkstyle

For configuring a new IDE :

• Install the Checkstyle plug-in (http://eclipse-cs.sf.net/update/)
  • version 5.1.0

• Each new MoDisco source project should have checkstyle enabled (context menu on the project, Checkstyle > Activate Checkstyle). Additional warnings are then computed on source code. A new builder is associated to the project.

• The local-check-config tag must be manually added to the .checkstyle file (see below) so that it points to the main checkstyle configuration file in org.eclipse.gmt.modisco.dev.core.

Here is an example checkstyle configuration file (.checkstyle). It ignores warnings on "Messages.java":

 <?xml version="1.0" encoding="UTF-8"?>
 <fileset-config file-format-version="1.2.0" simple-config="true">
   <local-check-config name="MoDisco" location="../org.eclipse.gmt.modisco.dev.core/checkstyle/MoDisco.checkstyle" type="project" description=""/>
   <fileset name="all" enabled="true" check-config-name="MoDisco" local="true">
     <file-match-pattern match-pattern="." include-pattern="true"/>
     <file-match-pattern match-pattern="Messages.java" include-pattern="false"/>
   </fileset>
 </fileset-config>

• Some generated files (such as EMF generated files) do not comply with the rules. For such files, the warnings can be ignored by selecting the package in section "Exclude from checking" in the checkstyle properties on the project, or checkstyle may be deactivated for the whole EMF generated project.

Reference: http://robertmarkbramprogrammer.blogspot.com/2007/07/eclipse-checkstyle-for-new-project.html

IP status

Note that Checkstyle is not an Eclipse.org tool. However, its source code is under the EPL, and its current use has been formally IP-validated for the MoDisco project:

• https://dev.eclipse.org/ipzilla/show_bug.cgi?id=3615 (initial CQ for EMO validation)
• http://dev.eclipse.org/mhonarc/lists/modeling-pmc/msg01391.html (email thread for Modeling PMC validation)

Also note that Checkstyle is not intended to be distributed with MoDisco.

Java Code Formatting

Each Contributor/Commiter is free to define its column number limit per line (global Java Editor setting in Eclipse IDE Preferences).

However in order to avoid some annoying version control differences, it is asked to not activate formatting save action (global Java Editor setting in Eclipse IDE Preferences) and only apply locally Eclipse formatter to the Java lines modified/added. It is asked to not define formatting settings locally to one java project, in order to let the developer work with its own formatting preferences.